How to fix error “Failed to compile : ./node_modules/@react-leaflet/core/esm/path.js 10:41 Module parse failed: Unexpected token (10:41)”

I am trying to create a react-typescript app along with leaflet. I used the command,

npm install leaflet react-leaflet @types/react @types/leaflet --save to install the dependencies.

But when I start the application it says,

    ./node_modules/@react-leaflet/core/esm/path.js 10:41
Module parse failed: Unexpected token (10:41)
File was processed with these loaders:
 * ./node_modules/babel-loader/lib/index.js
You may need an additional loader to handle the result of these loaders.
|   useEffect(function updatePathOptions() {
|     if (props.pathOptions !== optionsRef.current) {
>       const options = props.pathOptions ?? {};
|       element.instance.setStyle(options);
|       optionsRef.current = options;

Here’s my package.json

{
  "name": "aq-monitor",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@testing-library/jest-dom": "^5.12.0",
    "@testing-library/react": "^11.2.7",
    "@testing-library/user-event": "^12.8.3",
    "@types/jest": "^26.0.23",
    "@types/leaflet": "^1.7.0",
    "@types/node": "^12.20.13",
    "@types/react": "^17.0.5",
    "@types/react-dom": "^17.0.5",
    "antd": "^4.15.5",
    "leaflet": "^1.7.1",
    "react": "^17.0.2",
    "react-dom": "^17.0.2",
    "react-leaflet": "^3.2.0",
    "react-router-dom": "^5.2.0",
    "react-scripts": "4.0.3",
    "typescript": "^4.2.4",
    "web-vitals": "^1.1.2"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": [
      "react-app",
      "react-app/jest"
    ]
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  },
  "devDependencies": {
    "@types/react-router-dom": "^5.1.7"
  }
}

Here’s map/index.tsx

import React from 'react';
import './styles.css';
import L, { LatLngExpression } from "leaflet";
import "leaflet/dist/leaflet.css";
import {MapContainer, TileLayer, Marker, Popup} from 'react-leaflet';

const position : LatLngExpression = [59.91174337077401, 10.750425582038146];

export default function MapJar() {
    return (
        <MapContainer center={position} zoom={13} scrollWheelZoom={false}>
            <TileLayer
                attribution='&copy; <a href="http://osm.org/copyright">OpenStreetMap</a> contributors'
                url="https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png"
            />
            <Marker position={position}>
                <Popup>
                    A pretty CSS3 popup. <br /> Easily customizable.
                </Popup>
            </Marker>
        </MapContainer>
    );
};

I tried reinstalling dependencies several times but still didn’t work.

I understand this is a simple issue and an error that I am making but however, I have not been able to resolve this error.

Answer

I found a way to fix it.

Steps to fix:

Open your package.json file and edit your browserslist as follows.

From ?? Operator results in “Unexpected Token” err when used in package #9468:

 "browserslist": {
   "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
},

to

"browserslist": [
   ">0.2%",
  "not dead",
  "not op_mini all"
],

Once you’ve done this, delete the node_modules/.cache directory.

Then try npm install.

And npm start

Tadaaa!

References:

• ?? Operator results in “Unexpected Token” err when used in package #9468
• Module parse failed: Unexpected token (10:41) in @react-leaflet/core/esm/path.js #877